Method and apparatus for refining pulp



Oct. 13, 1931. CARNAHAN 1,827,279

METHOD AND APPARATUS FOR REFINING PULP Filed Dec. 9, 1929 Fig 3.

Fig 4! INVENTO R George/$ 1 Car/MA BY 1%1'2/7 1 6 [)0 W5, PlarVi/H Ec/mends ATTORN EYS Patented Oct. 13, 1931 UNITED STATES PATENT OFFICEGEORGE HOLMES CARNAIIAN, OF NEW YORK, N. Y., ASSIGNOR TO RUBBERSURFAGERS, INCL, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWAREMETHOD AND,APPARATUS FOR REFINING PULP Application filed December 9Thisinvention relates to an improved meth-t d and apparatus for treatingfibrous material and more particularly for treating pulp or paper stockwhereby the felting properties of the fibers are improved and, in thecase of vegetable fibers, the fiber substance is also hydrated whileminimizing the shortening of the fiber length which results from thecutting or breaking of the fibers when treated by the methods nowcommonly used. The

new method and apparatus also reduces the time usually required for thebeating treatment and produces a stock which improves the tea-ring,tensile, bursting and folding 1 strength of the paper made from it.

It has heretofore been the practice inthe paper and allied industries tosubject the ulp or stock to the action of a'refining mac 'ne such as thekollergang or edge runner. The

usual machine consists of a circular pan havthe weight of which is ingthe center portion thereof raised. A shaft projects through the raisedportion of the pan and fastened to it at right angles are two or moreaxles on which are mounted large rolls, carried largely by the bottom ofthe pan. The rolls are usuallg made of stone or other heavy material.

source of power is connected to the shaft so ,the pan in a circularpath.

and this also accommodates the machine to f the wear of the L Byreasonof the inherent hardnessor rlgthat the rolls may be caused totravel around The material to be treated is placed in the bottom of the'pan and the rolls pass'over 1t in their travel around the circular pathin stones.

idity of the stone or other heavy material used in the rolls, the rollshave a shearing and cutting effect on the pulp so thatthe fibers are1929. Serial No. 412,698.

0 a large extent cut oif with the result that the fibers so out are notonly shortened, but are left with more or less clean ends, instead ofends in a frayed or torn condition, which is desirable" to give the ulpgood felting properties. the rolls, is usually made of stone, and withconstant use both the roll and the bottom become worn irregularly due toirregularities in the composition of the stone used. The fibers caughtbetween these two hard and rigid surfaces and subjected to a rubbingaction are too often cut by irregularities in the hard surfaces of theroll and bed plate, and the fibers also tend to out each other.

With the present invention this cutting action is largely avoided andthe fiber bundles are disintegrated or separated into their individualfibers by a shearingaction substantially devoid of the cutting effectand the individual fibers are given the desired flattened and frayedcondition by a non-cutting, rub- 1 bing and crushing action. This isaccomplished by providing the rolls or the bed plate, and preferablyboth the rolls and the bed plate, with yielding resilient cushion-likesurfaces which have no cutting edges or surfaces and which exert on thepulp a rubbing effect without cutting, in place of the hard rigidsurfaces heretofore used. Preferably these surfaces are of rubber, therubber used beingof about the consistency of that used in rubberautomobile tires.

The hard rubber used throughout the spec ification and claims includesnot only rubber and rubber compositions in a strict sense, but alsorubber substances and equivalent compo-.

sitions having the proper rubber-like con-- sistencies and physicalcharacteristics for making yielding resilient surfaces suitable forperformiiig the method of the present invention. These cushion-likesurfaces of rubber or equivalent substances not only yield as a whole tothe pulp but are also ca able of yielding locally to bundles of fi rs orH bunches, thereby further minimizing the danger of injury to the fibersduring the treatment.

By the rotation of the shaft the rolls travel around the circularchannel of the pan and The bottom 0 the pan, as well as as I the fiberbundles and fibers are thus subjected substantially without cutting themto a shearing action characterized by rubbing, crushing and flatteningby the rolls so that the fiber bundles are separated into theirindividual fibers and the fibers are hydrated and frayed, as contrastedwith the usual cutting action, the degree of hydration depending largelyupon the severity and duration of the beating process.

As a result the felting properties of the fibers are improved and a moreuniform close web is obtained when the pulp passes over the aper machinewire, and the resulting paper 1s stronger than could be made from thesame stock with the beating methods heretofore commonly used. Thesqueezing, crushing and rubbing action between the relatively yieldingsurfaces tends to flatten out the fibers and to split them intofibrillae and to gelatinize or hydrate the fibers in a manner whichdevelops their felting and inherent strength-giving properties withoutobjectionable shortening of the fibers. The average length of thetreated pulp fiber is greater than in similar pulp SllbJGCtGCl to theaction of the ordinary -kollergang and the pulp is relatively free fromout fiber and blunt ends found in the.pulp beaten in anordinary'kollergang. Paper can be produced from the ulp resulting fromthe process of the present invention having higher tensile strength andbursting strength, higher tearing strength and higher folding strengththan with the same pulp beaten by usual methods. Moreover, the pulpitself is a free pulp from which the water readily drains away fasterthan with pulp treated to the same extent in an ordinary kollergang.Freeness, as that term is used in paper making, denotes the rate atwhich water drains away from the pulp on the wire of the papermakingmachine. The principal factors affecting freeness are the hydration ofthe individual fibers and the average length of the fibers. Hydrationtends to make a pulp slow that is, less free), but that is more thanoffset by the fiber length resulting from the method of the presentinvention. A free pulp is desirable in that it permits increasing thespeed of the paper making process, and hence reduces the cost, for thereason that the water will drain away faster from the pulp on the wireand the presses will express more water than from a less free pulp andhence the volume of the water which must subsequently be removed by thedryers is reduced. By reason of the increased-average length of thefibers produced by the new method of the present in- 'vention thefreeness of the pulp is improved notwithstanding the fibers areadequately hydrated.

The cushion-like surfaces also have the ef-' feet of increasing the areaof contact between the rolls and the bed stone. With the har and rigidsurfaces of the stone rolls and bed stones, the area of contact at anyinstant must necessarily be represented by a straight line across theface of the roll at the point of contact. With the yielding resilientsurfaces of the present invention the area of contact will be muchlarger due to the compression of the surfaces at the point of contactand any resultant bulging adjacent thereto. The fibers are thus treatedwith a twisting, rubbing motrate the new apparatus suitable forpracticing the new method:

Fig. 1 is a sectional elevation;

Fig. 2 is a plan view of part of Fig. 1; and

Figs. 3 and 4 are detail views on an enlarged scale in sectionillustrating different constructions of the yielding resilient surfacesapplied to the rolls.

The pulp or sock to be treated is continuously fed into the pan 5 of thekollergang by means of spiral feed 6 and screw conveyor 7 or by anyother appropriate means of maintainmg a constant feed. The kollergangmay be provided with two or more rolls 8 and the machine illustrated isshown as having three rolls. These rolls are made of a dense materialwhich lends weight to them and enables them to crush the pulp fibers asthey pass around the pan. The rolls 8 are provided with a v rubbersurface approximately one half or more inches thick which may be made instrips and cemented to the rolls or may be vulcanized directly thereon.

The bottom of the pan or bed stone 9 is provided with a rubber surfacing10 of any desired thickness which may be applied in the same manner asthe rubber surfacing on the rolls. The rolls 8 are mounted on axles 11which in turn are fastened to the central shaft 12. The shaft 12 isprovided with a bevel gear 13 by means of which power is applied to theshaft to cause the rolls to travel around the bottom of the pan 5.

The pulp or stock is withdrawn continuously through the opening 14. Thisopening is provided with a weir 15 which may be lowered or raised asdesired to decrease or increase the depth of the body of pulp or stockbeing treated in the pan 5. The stock passes into chamber 16 from whichit is removed by spiral conveyor to another step in the paper makingprocess, or to another treatment in another kollergang; By regulatingthe height of the weir and the rate of feed to the pan, the length oftime to which the pulp is subjected to the treatment can be regulated.

For example, with a relatively large body of plate, the higher portions17 are flattened so that a kneading action is applied to the fibers,which amplifies the rubbing and crushing action of the process of thisinvention with resulting increase in hydrationof the fibers and theseparation of the bundles of fibers. The effect of having this wavyrubber surface on the roll is to intensify the treatment ofthe fibers ineach revolution of the rolls with resulting speeding up of the processand conse uent saving in time.

ith a surface simiar to that shown in Fig. 3 in which the raisedportions 18 are relatively more prominent, the said raised portions donot become entirely flattened when the surface of the rolls comes intocontact with the bed plate. The raised portions are flattened somewhat,but the depressions between the raised portions are not entirelyeliminated, so that the depressed portions of the roll do not touch thebed plate. This results in an even more pronounced kneading effect onthe fibers with resulting increased efiiciency in each revolution of aroll and tends to hold the fibers under the roll and prevent theirslipping out ahead of the roll. This also tends to increase theefliciency of the operation as a whole.

I When the rolls travel around the bed plate, the pulp 1s subjected tothe kneading action of I the resilient yielding surface, certain formsof which have been, described by way of illustration, the effect is torub, crush, abrade and pull the pulp without substantlal cutting so asto separate bundles of fibers roll and bed plate surfaces, one at leastof said surfaces being of substantial thickness and resilient andyieldable, whereby the fibrous material is subjected to the squeezingand rubbing action of the contacting surfaces having a substantial areaof surface yieldably contacting with each other.

2. The process according to the preceding claim in which both surfacescontacting with each other are resilient and yieldable whereby thefibrous material is subjected to a squeezing and rubbing action betweensuch yieldable surfaces.

3. [A kollergang comprising rolls and a bed plate therefor, said rollshaving resilient yieldable surfaces of substantial thickness which havea substantial surface contact with the bed plate during operation.

4. A kollergang comprising rolls and a bed plate therefor, the saidplate with which the rolls come in contact having a yieldable resilientsurface of substantial-thickness which has a substantial area of contactwith the rolls during operation.

5. A kollergang com risin' rolls and a bed plate therefor, both t e rols and the bed plate having resilient and yielding surfaces ofsubstantial thickness which have substantial surface areas in contactwith each other during operation.

into individual fibers and to fray out the ends ile the .presentinvention is of particular value for the beating of chemical wood fiber,it includes in its broader aspects the refining of other materials whichrequire similar treatment.

I claim 1. The method of treating fibrous material, whichcomprises-subjecting sucli material to a combined squeezing and rubbingtreatment in a kollergang having contacting

